Hydroprocessing of hydrocarbons

ABSTRACT

A process for hydrotreating (hydroprocessing) hydrocarbons and mixtures of hydrocarbons utilizing a catalytic composite of a porous carrier material, a platinum or palladium component, an iridium component and a germanium component, in which process there is effected a chemical consumption of hydrogen. A specific example of one such catalyst is a composite of a crystalline aluminosilicate, a platinum component, an iridium component and a germanium component, for utilization in a hydrocracking process. Other hydrocarbon hydroprocesses are directed toward the hydrogenation of aromatic nuclei, the ring-opening of cyclic hydrocarbons, desulfurization, denitrification, hydrogenation, etc.

RELATED APPLICATIONS

The present application is a division of my copending application, Ser.No. 443,046 filed Feb. 15, 1974, now U.S. Pat. No. 3,900,386, which is aContinuation-in-Part of my application, Ser. No. 365,782, now U.S. Pat.No. 3,839,193, filed May 31, 1973, which, in turn, is aContinuation-in-Part of my application, Ser. No. 27,457 filed Apr. 10,1970, now abandoned; all the teachings of these applications areincorporated herein by specific reference thereto.

APPLICABILITY OF INVENTION

The present invention encompasses the use of a catalytic composite of aporous carrier material, a platinum or palladium component, an iridiumcomponent and a germanium component in the hydrotreating of hydrocarbonsand mixtures of hydrocarbons. As utilized herein, the term"hydrotreating" is intended to be synonymous with the term"hydroprocessing", which involves the conversion of hydrocarbons atoperating conditions selected to effect a chemical consumption ofhydrogen. Included within the processes intended to be encompassed bythe term hydroprocessing are hydrocracking, aromatic hydrogenation,ring-opening, hydrorefining (for nitrogen removal and olefinsaturation), desulfurization (often included in hydrorefining) andhydrogenation, etc. As will be recognized, one common attribute of theseprocesses, and the reactions being effected therein, is that they areall "hydrogen-consuming", and are, therefore, exothermic in nature.

The individual characteristics of the foregoing hydrotreating processes,including preferred operating conditions and techniques, will behereinafter described in greater detail. The subject of the presentinvention is the use of a catalytic composite which has exceptionalactivity and resistance to deactivation when employed in ahydrogen-consuming process. Such processes require a catalyst havingboth a hydrogenation function and a cracking function. Morespecifically, the present process uses a dual-function catalyticcomposite which enables substantial improvements in those hydroprocessesthat have traditionally used a dual-function catalyst. The particularcatalytic composite constitutes a porous carrier material, a platinum orpalladium component, an iridium component and a germanium component;specifically, an improved hydrocracking process utilizes a crystallinealuminosilicate carrier material, a platinum component, an iridiumcomponent and a germanium component for improved activity, productselectivity and operational stability characteristics.

Composites having dual-function catalytic activity are widely employedin many industries for the purpose of accelerating a wide spectrum ofhydrocarbon conversion reactions. Generally, the cracking function isthought to be associated with an acid-acting material of the porous,adsorptive refractory inorganic oxide type which is typically utilizedas the carrier material for a metallic component from the metals, orcompounds of metals, of Groups V through VIII of the Periodic Table, towhich the hydrogenation function is generally attributed.

Catalytic composites are used to promote a wide variety of hydrocarbonconversion reactions such as hydrocracking, isomerization,dehydrogenation, hydrogenation, desulfurization, reforming,ring-opening, cyclization, aromatization, alkylation andtransalkylation, polymerization, cracking, etc., some of which reactionsare hydrogen-producing while others are hydrogen-consuming. In using theterm "hydrogen-consuming", I intend to exclude those processes whereinthe only hydrogen consumption involves the saturation of light olefins,resulting from undesirable cracking, which produces the light paraffins,methane, ethane and propane. It is to the latter group of reactions,hydrogen-consuming, that the present invention is applicable. In manyinstances, the commercial application of these catalysts is in processeswhere more than one of these reactions proceed simultaneously. Anexample of this type of process is a hydrocracking process whereincatalysts are utilized to effect selective hydrogenation and cracking ofhigh molecular weight materials to produce a lower-boiling, morevaluable output stream. Another such example would be the conversion ofaromatic hydrocarbons into jet fuel components, principally straight, orslightly branched paraffins.

Regardless of the reaction involved, or the particular process, it isvery important that the catalyst exhibit not only the capability toperform its specified functions initially, but also perform themsatisfactorily for prolonged periods of time. The analytical termsemployed in the art to measure how efficient a particular catalystperforms its intended functions in a particular hydrocarbon conversionprocess, are activity, selectivity and stability. For the purpose ofdiscussion, these terms are conveniently defined herein, for a givencharge stock, as follows: (1) activity is a measure of the ability ofthe catalyst to convert a hydrocarbon feed stock into products at aspecified severity level, where severity level alludes to the operatingconditions employed--the temperature, pressure, liquid hourly spacevelocity and hydrogen concentration; (2) selectivity refers to theweight percent or volume percent of the reactants that are convertedinto the desired product and/or products; (3) stability connotes therate of change of the activity and selectivity parameters withtime--obviously, the smaller rate implying the more stable catalyst.With respect to a hydrogen-consuming process, for example hydrocracking,activity, stability and selectivity are similarly defined. Thus,"activity" connotes the quantity of charge stock, boiling above a giventemperature, which is converted to hydrocarbons boiling below the giventemperature. "Selectivity" refers to the quantity of converted chargestock which boils below the desired end point of the product, as well asabove a minimum specified initial boiling point. "Stability" connotesthe rate of change of activity and selectivity. Thus, for example, wherea gas oil, boiling above about 650°F., is subjected to hydrocracking,activity connotes the conversion of 650°F.-plus charge stock to650°F.-minus product. Selectivity can allude to the quantity ofconversion into gasoline boiling range hydrocarbons--i.e., pentanes andheavier, normally liquid hydrocarbons boiling up to about 400°F.Stability might by conveniently expressed in terms of temperatureincrease required during various increments of catalyst life, in orderto maintain the desired activity.

As is well known to those skilled in the art, the principal cause ofobserved deactivation or instability of a dual-function catalyst isassociated with the fact that coke forms on the surface of the catalystduring the course of the reaction. More specifically, in the varioushydrocarbon conversion processes, and especially those which arecategorized as hydrogen-consuming, the operating conditions utilizedresult in the formation of high molecular weight, black, solid orsemi-solid, hydrogen-poor carbonaceous material which coats the surfaceof the catalyst and reduces its activity by shielding its active sitesfrom the reactants. Accordingly, a major problem facing workers in thisarea is the development of more active and selective catalyticcomposites that are not as sensitive to the presence of thesecarbonaceous materials and/or have the capability to suppress the rateof formation of these materials at the operating conditions employed ina particular process.

I have now found a dual-function catalytic composite which possessesimproved activity, selectivity and stability when employed in thehydroprocessing of hydrocarbons, wherein there is effected a chemicalconsumption of hydrogen. In particular, I have found that the use of acatalytic composite of a platinum or palladium component, an iridiumcomponent and a germanium component with a porous carrier materialimproves the overall operation of these hydrogen-consuming processes.Moreover, I have determined that a catalytic composite of a crystallinealuminosilicate carrier material, a platinum component, an iridiumcomponent and a germanium component, when utilized in a process forhydrocracking hydrocarbonaceous material into lower-boiling hydrocarbonproducts, affords substantial improvement in performance and results. Asindicated, the present invention essentially involves the use of acatalyst in which a germanium component and an iridium component hasbeen added to a dual-function conversion catalyst, and enables theperformance characteristics of the process to be sharply and materiallyimproved.

An essential condition associated with the acquisition of this improvedperformance is the oxidation state of the germanium component utilizedin this catalyst. As a result of my investigations, I have determinedthat the germanium component must be utilized in a positive oxidationstate (i.e., either +2 or +4) and that the germanium component must beuniformly distributed throughout the porous carrier material.Furthermore, the catalyst must be prepared under carefully controlledconditions as will be explained hereinafter. In the case of ahydrocracking process, one of the principal advantages associated withthe use of the novel catalyst of the present invention involves theacquisition of the capability to operate in a stable manner in a highseverity operation. In short, the present invention essentially involvesthe finding that the addition of a controlled amount of a germaniumcomponent, in a positive oxidation state, to a dual-function hydrocarbonconversion catalyst containing a platinum or palladium component enablesperformance characteristics of the catalyst to be sharply and materiallyimproved when used in a hydrogen-consuming process.

OBJECTS AND EMBODIMENTS

An object of the present invention is to afford a process for thehydroprocessing of a hydrocarbon, or mixture of hydrocarbons. Acorollary objective is to improve the selectivity and stability ofhydroprocessing utilizing a highly active, germaniumcomponent-containing and iridium component-containing catalyticcomposite.

A specific object of my invention resides in the improvement ofhydrogen-consuming processes including hydrocracking, hydrorefining,ring-opening for jet fuel production, hydrogenation of aromatichydrocarbons, desulfurization, denitrification, etc. Therefore, in oneembodiment, the present invention encompasses a hydrocarbon hydroprocesswhich comprises reacting a hydrocarbon with hydrogen at conditionsselected to effect chemical consumption of hydrogen and in contact witha catalytic composite of a platinum or palladium component, an iridiumcomponent, a germanium component and a porous carrier material. Inanother embodiment, the operating conditions include a pressure of from400 to about 5,000 psig., an LHSV (defined as volumes of liquidhydrocarbon charge per hour per volume of catalyst disposed in thereaction zone) of from 0.1 to about 10.0, a hydrogen circulation rate offrom 1,000 to about 50,000 scf./Bbl. and a maximum catalyst temperatureof from 200°F. to about 900°F.

In another embodiment, the process is further characterized in that thecatalytic composite is reduced and sulfided prior to contacting thehydrocarbon feed stream. In still another embodiment, my inventioninvolves a process for hydrogenating a coke-forming hydrocarbondistillate containing di-olefinic and mono-olefinic hydrocarbons, andaromatics, which process comprises reacting said distillate withhydrogen, at a temperature below about 500°F., in contact with acatalytic composite of an alumina-containing refractory inorganic oxide,a platinum or palladium component, an alkali metal component, an iridiumcomponent and a germanium component, and recovering anaromatic/mono-olefinic hydrocarbon concentrate substantially free fromconjugated di-olefinic hydrocarbons.

Another embodiment affords a catalytic composite comprising asubstantially pure crystalline aluminosilicate material, at least about90.0% by weight of which is zeolitic, a platinum or palladium component,an iridium component and a germanium component.

Other objects and embodiments of my invention relate to additionaldetails regarding preferred catalytic ingredients, the concentration ofcomponents in the catalytic composite, methods of catalyst preparation,individual operating conditions for use in the various hydrotreatingprocesses, preferred processing techniques and the like particularswhich are hereinafter given in the following, more detailed summary ofmy invention.

SUMMARY OF THE INVENTION

As hereinabove set forth, the present invention involves thehydroprocessing of hydrocarbons and mixtures of hydrocarbons, utilizinga particular catalytic composite. This catalyst comprises a porouscarrier material having combined therewith a platinum or palladiumcomponent, an iridium component and a germanium component; in manyapplications, the catalytic composite will also contain a halogencomponent, and in some select applications, an alkali metal oralkaline-earth metal component. Considering first the porous carriermaterial, it is preferred that it be a porous, adsorptive, high-surfacearea support having a surface area of about 25 to about 500 squaremeters per gram. The porous carrier material is necessarily relativelyrefractory with respect to the operating conditions employed in theparticular hydrotreating process, and it is intended to include carriermaterials which have traditionally been utilized in dual-functionhydrocarbon conversion catalysts. In particular, suitable materials areselected from the group of amorphous refractory inorganic oxidesincluding alumina, titania, zirconia, chromia, magnesia, thoria, boria,silica-alumina, silica-magnesia, chromia-alumina, alumina-boria,alumina-silica-boron phosphate, silica-zirconia, etc. When of theamorphous type, the preferred material is a composite of alumina andsilica with silica being present in an amount of about 10.0% to about90.0% by weight.

In many hydroprocessing applications of the present invention,particularly hydrocracking heavy hydrocarbonaceous material to producelower-boiling hydrocarbon products, the carrier material will constitutea crystalline aluminocsilicate, often referred to as being zeolitic innature. This may be naturally-occurring, or synthetically prepared, andincludes mordenite, faujasite, Type A or Type U molecular sieves, etc.When utilized as the carrier material, the zeolitic material may be inthe hydrogen form, or in a form which has been treated with multi-valentcations. As hereinabove set forth, the porous carrier material, for usein the process of the present invention, is a refractory inorganicoxide, either alumina in and of itself, or in combination with one ormore other refractory inorganic oxides, and particularly in combinationwith silica. When utilized as the sole component of the carriermaterial, the alumina may be of the gamma-, eta, or theta-alumina type,with gamma-, or eta-alumina giving the best results. In addition, thepreferred carrier materials have an apparent bulk density of about 0.30to about 0.70 gm./cc. and surface area characteristics such that theaverage pore diameter is about 20 to about 300 Angstroms, the porevolume is about 0.10 to about 1.0 milliliters per gram and the surfacearea is about 100 to about 500 square meters per gram. Whatever type ofrefractory inorganic oxide is employed, it may be activated prior to useby one or more treatments including drying, calcination steaming, etc.For example, the alumina carrier may be prepared by adding a suitablealkaline reagent, such as ammonium hydroxide, to a salt of aluminum,such as aluminum chloride, aluminum nitrate, etc., in an amount to forman aluminum hydroxide gel which, upon drying and calcination, isconverted to alumina. The carrier material may be formed in any desiredshape such as spheres, pills, cakes, extrudates, powders, granules,etc., and may further be utilized in any desired size.

When a crystalline aluminoscilicate, or zeolitic material, is intendedfor use as the carrier, it may be prepared in a number of ways. Onecommon way is to mix solutions of sodium silicate, or colloidal silica,and sodium aluminate, and allow these solutions to react to form a solidcrystalline aluminosilicate. Another method is to contact a solidinorganic oxide, from the group of silica, alumina, and mixturesthereof, with an aqueous treating solution containing alkali metalcations (preferably sodium) and anions selected from the group ofhydroxyl, silicate and aluminate, and allow the solid-liquid mixture toreact until the desired crystalline aluminosilicate has been formed. Oneparticular method is especially preferred when the carrier material isintended to be a crystalline aluminosilicate. This stems from the factthat the method can produce a carrier material of substantially purecrystalline aluminosilicate particles. In employing the term"substantially pure", the intended connotation is an aggregate particleat least 90.0% by weight of which is zeolitic. Thus, this carrier isdistinguished from an amorphous carrier material, or prior art pillsand/or extrudes in which the zeolitic material might be dispersed withinan amorphous matrix with the result that only about 40.0% to about 70.0%by weight of the final particle is zeolitic. The preferred method ofpreparing the carrier material produces crystalline aluminosilicates ofthe faujasite modification, and utilizes aqueous solutions of colloidalsilica and sodium aluminate. Colloidal silica is a suspension in whichthe suspended particles are present in very finely divided form--i.e.,having a particle size from about 1 to about 500 millimicrons indiameter. The type of crystalline aluminosilicate which is produced isprimarily dependent upon the conditions under which crystallizationoccurs, with the SiO₂ /Al₂ O₃ ratio, the Na₂ O/SiO₂ ratio, the H₂ O/Na₂O ratio, temperature and time being the important variables.

After the solid crystalline aluminosilicate has been formed, the motherliquor is separated from the solids by methods such as decantation orfiltration. The solids are water-washed and filtered to removeundesirable ions, and to reduce the quantity of amorphous material, andare then reslurried in water to a solids concentration of about 5.0% toabout 50.0%. The cake and the water are violently agitated andhomogenized until the agglomerates are broken and the solids areuniformly dispersed in what appears to be a colloidal suspension. Thesuspension is then spray dried by conventional means such as pressuringthe suspension through an orifice into a hot, dry chamber. The solidparticles are withdrawn from the drying chamber and are suitable forforming into finished particles of desired size and shape. The preferredform of the finished particles is a cylindrical pill, and these may beprepared by introducing the spray-dried particles directly into apilling machine without the addition of any extraneous lubricant orbinder. The pilling machines are adjusted to produce particles having acrushing strength of from 2 to 20 pounds, and preferably from 5 to 15pounds. The pilled faujasite carrier material, of which at least about90.0% by weight is zeolitic, is activated catalytically by coverting thesodium form either to the divalent ion form, the hydrogen form ormixtures thereof.

One essential constituent of the composite of the present invention is agermanium component, and it is an essential feature of the catalyst usedin hydroprocessing according to the present invention, that thegermanium component is present in the composite in an oxidation stateabove that of the elemental metal. That is to say, the germaniumcomponent necessarily exists within the catalytic composite in eitherthe +2 or +4 oxidation state, the latter being the most likely state.Accordingly, the germanium component will be present in the composite asa chemical compound, such as the oxide, sulfide, halide, etc., whereinthe germanium is in the required oxidation state, or as a chemicalcombination with the carrier material in which combination the germaniumexists in this higher oxidation state. On the basis of the evidenceconcurrently available, it is believed that the germanium component inthe subject composite exists as germanous or germanic oxide. It isimportant to note that this limitation on the state of the germaniumcomponent requires extreme care in the preparation and use of thesubject composite in order to insure that it is not subjected to hightemperature reduction conditions (reduction at temperatures above1000°F.) effective to produce the germanium metal. This germaniumcomponent may be incorporated in the catalytic composite in any suitablemanner known to the art such as by co-precipitation or cogellation withthe porous carrier material, ion-exchange with the gelled carriermaterial or impregnation with the carrier material either after orbefore it is dried and calcined. It is to be noted that it is intendedto include within the scope of the present invention all conventionalmethods for incorporating a metallic component in a catalytic compositeand the particular method of incorporation used is not deemed to be anessential feature of the present invention. One method of incorporatingthe germanium component into the catalytic composite involvesco-precipitating the germanium component during the preparation of thecarrier material. This method typically involves the addition of asuitable soluble germanium compound such as germanium tetrachloride tothe inorganic oxide hydrosol and then combining the hydrosol with asuitable gelling agent and dropping the resultant mixture into an oilbath maintained at elevated temperatures. The droplets remain in the oilbath unitl they set and form hydrogel spheres. The spheres are withdrawnfrom the oil bath and subjected to specific aging treatments in oil andin an ammoniacal solution. The aged spheres are washed and dried at atemperature of about 200°F. to 400°F., and thereafter calcined at anelevated temperature of about 850°F. to about 1300°F. Further details ofspherical particle production may be found in U.S. Pat. No. 2,620,314,issued to James Hoekstra. After drying and calcining the resultinggelled carrier material there is obtained an intimate combination ofalumina and germanium oxide. A preferred method of incorporating thegermanium component into the catalytic composite involves utlization ofa soluble, decomposable compound of germanium to impregnate the porouscarrier material. In general, the solvent used in this impregnation stepis selected on the basis of the capability to dissolve the desiredgermanium compound and is preferably an aqueous, or alcoholic solution.Thus, the germanium component may be added to the carrier material bycommingling the latter with a solution of a suitable germanium salt orsuitable compound of germanium such as germanium tetrachloride,germanium difluoride, germanium tetrafluoride, germanium di-iodide,germanium monosulfide, and the like compounds. In general, the germaniumcomponent can be impregnated either prior to, simultaneously with, orafter the other metallic components are added to the carrier material.However, I have found that excellent results are obtained when thegermanium component is impregnated simultaneously with the othermetallic components. In fact, I have determined that a preferredimpregnation solution contains chloroplatinic acid, hydrogen chloride,chloroiridic acid, and germanous oxide dissolved in chorine water,especially when the catalyst is intended to contain combined chlorine. Ihave also determined that another impregnation solution compriseschloroplatinic acid, hydrogen chloride, chloroiridic acid and germaniumtetrachloride dissolved in ethanol. Best results are believed to beobtained when this component exists in the composite as germanium oxide.Following the impregnation step, the resulting composite is dried andcalcined as explained hereinafter.

Regardless of which germanium compound is used in the preferredimpregnation step, it is important that the germanium component beuniformly distributed throughout the carrier material. It is preferredto use a volume ratio of impregnation solution to carrier material of atleast 1.5:1 and preferably about 2:1 to about 10:1 or more. Similarly,it is preferred to use a relatively long contact time during theimpregnation step ranging from about one-fourth hour up to aboutone-half hour or more before drying to remove excess solvent in order toinsure a high dispersion of the germanium component on the carriermaterial. The carrier material is, likewise, preferably constantlyagitated during this preferred impregnation step.

As previously indicated, the catalyst for use in the process of thepresent invention also contains a platinum or palladium component.Although the process of the present invention is specifically directedto the use of a catalytic composite containing platinum, it is intendedto include palladium. The platinum or palladium component, for exampleplatinum, may exist within the final catalytic composite as a compoundsuch as an oxide, sulfide, halide, etc., or in an elemental state. Theplatinum or palladium component generally comprises about 0.01% to about2.0% by weight of the final composite, calculated on an elemental basis.Excellent results are obtained when the catalyst contains about 0.3% toabout 0.9% by weight of platinum or palladium.

The platinum or palladium component may be incorporated within thecatalytic composite in any suitable manner including co-precipitation orcogellation with the carrier material, ion-exchange or impregnation. Apreferred method of preparation involves the utilization of awater-soluble compound of platinum or palladium in an impregnationtechnique. Thus a platinum component may be added to the carriermaterial by commingling the latter with an aqueous solution ofchloroplatinic acid. Other water-soluble compounds of platinum may beemployed, and include ammonium chloroplatinate, platinum chloride,dinitro diamino platinum, etc. The use of a platinum chloride compound,such as chloroplatinic acid, is preferred since it facilitates theincorporation of both the platinum component and at least a minorquantity of the halogen component in a single step. In addition, it isgenerally preferred to impregnate the carrier material after it has beencalcined in order to minimize the risk of washing away the valuableplatinum or palladium metal compounds, however, in some instances it mayprove advantageous to impregnate the carrier material when it exists ina gelled state. Following impregnation, the composite will generally bedried at a temperature of about 200°F. to about 400°F., for a period offrom 2 to about 24 hours, or more, and finally calcined at a temperatureof about 700°F. to 1100°F., in an atmosphere of air, for a period ofabout 0.5 to about 10 hours.

Yet another essential ingredient of the present catalytic composite isan iridium component. It is of fundamental importance that substantiallyall the iridium component exists within the catalytic composite of thepresent invention in the elemental state and the subsequently describedreduction procedure is designed to accomplish this objective. Theiridium component may be utilized in the composite in any amount whichis catalytically effective, with the preferred amount being about 0.1 toabout 2 wt. % thereof, calculated on an elemental iridium basis.Typically best results are obtained with about 0.05 to about 1 wt. %iridium. It is additionally, preferred to select the specific amount ofiridium from within this broad weight range as a function of the amountof the platinum or palladium component, on an atomic basis, as isexplained hereinafter.

This iridium component may be incorporated into the catalytic compositein any suitable manner known to those skilled in the catalystformulation art which results in a relatively uniform dispersion ofiridium in the carrier material. In addition, it may be added at anystage of the preparation of the composite-- either during preparation ofthe carrier material or thereafter-- and the precise method ofincorporation used is not deemed to be critical. However best resultsare thought to be obtained when the iridium component is relativelyuniformly distributed throughout the carrier material, and the preferredprocedures are the ones known to result in a composite having thisrelatively uniform distribution. One acceptable procedure forincorporating this component into the composite involves cogelling orcoprecipitating the iridium component during the preparation of thecarrier material. A preferred way of incorporating this component is animpregnation step wherein the porous carrier material is impregnatedwith a suitable iridium-containing solution either before, during orafter the carrier material is calcined. Preferred impregnation solutionsare aqueous solutions of water soluble, decomposable iridium componentssuch as iridium tribromide, iridium dichloride, iridium tetrachloride,iridium oxalic acid, iridium sulfate, potassium iridochloride,chloroiridic acid and the like compounds. Best results are ordinarilyobtained when the impregnation solution is an aqueous solution ofchloroiridic acid or sodium chloroiridate. This component can be addedto the carrier material, either prior to, simultaneously with or afterthe other metallic components are combined therewith. Best results areusually achieved when this component is added simultaneously with theother metallic components. In fact, excellent results are obtained, asreported in the examples, with a one step impregnation procedure usingan aqueous solution comprising chloroplatinic or chloropalladic acid,chloroiridic acid, hydrochloric acid and germanium tetrachloridedissolved in anhydrous alcohol.

Although not essential to successful hydroprocessing in all cases, infact detrimental in some, a halogen component may be incorporated intothe catalytic composite. Accordingly, a preferred catalytic composite,for use in the present process, comprises a combination of a platinum orpalladium component, a germanium component, an iridium component and ahalogen component. Although the precise form of the chemistry of theassociation of the halogen component with the carrier material andmetallic components is not accurately known, it is customary in the artto refer to the halogen component as being combined with the carriermaterial, or with the other ingredients of the catalyst. The combinedhalogen may be either fluorine, chlorine, iodine, bromine, or mixturesthereof. Of these fluorine and particularly chlorine are preferred forthe hydrocarbon hydroprocesses encompassed by the present invention. Thehalogen may be added to the carrier material in any suitable manner, andeither during preparation of the carrier or before, or after theaddition of the other components. For example, the halogen may be addedat any stage of the preparation of the carrier material, or to thecalcined carrier material, as an aqueous solution of an acid such ashydrogen fluoride, hydrogen chloride, hydrogen bromide, hydrogen iodide,etc. The halogen component or a portion thereof may be composited withthe carrier material during the impregnation of the latter with the mealcomponents. The inorganic oxide hydrosol, which is typically utilized toform an amorphous carrier material, may contain halogen and thuscontribute at least a portion of the halogen component to the finalcomposite. The quantity of halogen is such that the final catalyticcomposite contains about 0.1% to about 1.5% by weight, and preferablyfrom about 0.5% to about 1.2%, calculated on an elemental basis.

Regarding the preferred amounts of the various metallic components ofthe subject catalyst, I have found it to be good practice to specify theamounts of the iridium component and the germanium component as afunction of the amount of the platinum or palladium component. On thisbasis, the amount of the iridium component is ordinarily selected sothat the atomic ratio of iridium to platinum or palladium metalcontained in the composite is about 0.1:1 to about 2:1, with thepreferred range being about 0.25:1 to about 1.5:1. Similarly, the amountof the germanium component is ordinarily selected to produce a compositecontaining an atomic ratio of germanium to platinum or palladium metalof about 0.3:1 to about 10:1, with the preferred range being about 0.6:1to about 6:1.

Another significant parameter for the instant catalyst is the "totalmetals content" which is defined to be the sum of the platinum orpalladium component, the iridium component and the germanium component,calculated on an elemental metal basis. Good results are ordinarilyobtained with the subject catalyst when this parameter is fixed at avalue of about 0.15 to about 3 wt. %, with best results ordinarilyachieved at a metals loading of about 0.3 to about 2 wt. %.

In embodiments of the present invention wherein the instant trimetalliccatalytic composite is used for the hydrogenation hydrocarbons, it isordinarily a preferred practice to include an alkali or alkaline earthmetal component in the composite. More precisely, this optionalcomponent is selected from the group consisting of the compounds of thealkali metals -- cesium, rubidium, potassium, sodium, and lithium -- andthe compounds of the alkaline earth metals -- calcium, strontium, bariumand magnesium. Generally, good results are obtained in these embodimentswhen this component constitutes about 1 to about 5 wt. % of thecomposite, calculated on an elemental basis. This optional alkali oralkaline earth metal component can be incorporated in the composite inany of the known ways, with impregnation with an aqueous solution of asuitable water-soluble, decomposable compound being preferred.

An optional ingredient for the trimetallic catalyst of the presentinvention is a Friedel-Crafts metal halide component. This ingredient isparticularly useful in hydrocarbon conversion embodiments of the presentinvention wherein it is preferred that the catalyst utilized has astrong acid or cracking function associated therewith -- for example, anembodiment wherein hydrocarbons are to be hydrocracked or isomerizedwith the catalyst of the present invention. Suitable metal halides ofthe Friedel-Crafts type include aluminum chloride, aluminum bromide,ferric chloride, ferric bromide, zinc chloride and the like compounds,with the aluminum halides and particularly aluminum chloride ordinarilyyielding best results. Generally, this optional ingredient can beincorporated into the composite of the present invention by any of theconventional methods for adding metallic halides of this type; however,best results are ordinarily obtained when the metallic halide issublimed onto the surface of the carrier material according to thepreferred method disclosed in U.S. Pat. No. 2,999,074. The component cangenerally be utilized in any amount which is catalytically effective,with a value selected from the range of about 1 to about 100 wt. % ofthe carrier material generally being preferred. When used in many of thehydrogen-consuming processes hereinbefore described, the foregoingquantities of metallic components will be combined with a carriermaterial of alumina and silica, wherein the silica concentration is10.0% to about 90.0% by weight.

Regardless of the details of how the components of the catalyst arecombined with the porous carrier material, the final catalyst generallywill be dried at a temperature of about 200 to about 600°F. for a periodof at least about 2 to about 24 hours or more, and finally calcined oroxidized at a temperature of about 700°F. to about 1100°F. in an airatmosphere for a period of about 0.5 to about 10 hours in order toconvert substantially all of the metallic components substantially tothe oxide form. Because a halogen component may be utilized in thecatalyst, best results are generally obtained when the halogen contentof the catalyst is adjusted during the calcination step by including ahalogen or a halogen-containing compound in the air atmosphere utilized.In particular, when the halogen component of the catalyst is chlorine,it is preferred to use a mole ratio of H₂ O to HCl of about 5:1 to about100:1 during at least a portion of the calcination step in order toadjust the final chlorine content of the catalyst to a range of about0.5 to about 1.5 wt. %.

It is an essential feature of the present invention that the resultantoxidized catalytic composite is subjected to a substantially water-freereduction step prior to its use in the conversion of hydrocarbons. Thisstep is designed to selectively reduce the platinum or palladium andiridium components to the corresponding metals and to insure a uniformand finely divided dispersion of these metallic components throughoutthe carrier material, while maintaining the germanium component in apositive oxidation state. Preferably, substantially pure and dryhydrogen (i.e., less than 20 vol. ppm. H₂ O) is used as the reducingagent in this step. The reducing agent is contacted with the oxidizedcatalyst at conditions including a temperature of about 800°F. to about1200°F. and a period of time of about 0.5 to 2 hours effective to reducesubstantially all of the platinum or palladium and iridium components totheir elemental metallic state while maintaining the germanium componentin an oxidation state above that of the elemental metal. This reductiontreatment may be performed in situ as part of a start-up sequence ifprecautions are taken to predry the plant to a substantially water-freestate and if substantially water-free hydrogen is used.

The resulting reduced catalytic composite may, in some cases, bebeneficially subjected to a presulfiding operation designed toincorporate in the catalytic composite from about 0.05 to about 0.5 wt.% sulfur calculated on an elemental basis. Preferably, this presulfidingtreatment takes place in the presence of hydrogen and a suitablesulfur-containing compound such as hydrogen sulfide, lower molecularweight mercaptans, organic sulfides, etc. Typically, this procedurecomprises treating the selectively reduced catalyst with a sulfiding gassuch as a mixture of hydrogen and hydrogen sulfide having about 10 molesof hydrogen per mole of hydrogen sulfide at conditions sufficient toeffect the desired incorporation of sulfur, generally including atemperature ranging from about 50°F. up to about 1100°F. or more. It isgenerally a good practice to perform this presulfiding step undersubstantially water-free conditions.

According to the present invention, a hydrocarbon charge stock andhydrogen are contacted with a trimetallic catalyst of the type describedabove in a hydrocarbon conversion zone. This contacting may beaccomplished by using the catalyst in a fixed bed system, a moving bedsystem, a fluidized bed system, or in a batch type operation; however,in view of the danger of attrition losses of the valuable catalyst andof well known operational advantages, it is preferred to use a fixed bedsystem. In this system, a hydrogen-rich gas and the charge stock arepreheated by any suitable heating means to the desired reactiontemperature and then are passed, into a conversion zone containing afixed bed of the catalyst type previously characterized. It is, ofcourse, understood that the conversion zone may be one or more separatereactors with suitable means therebetween to insure that the desiredconversion temperature is maintained at the entrance to each reactor. Itis also important to note that the reactants may be contacted with thecatalyst bed in either upward, downward, or radial flow fashion with thelatter being preferred. In addition, the reactants may be in the liquidphase, a mixed liquid-vapor phase, or a vapor phase when they contactthe catalyst.

The operating conditions imposed upon the reaction zones are dependentupon the particular hydroprocessing being effected. However, theseoperating conditions will include a pressure from about 400 to about5,000 psig., a liquid hourly space velocity of about 0.1 to about 10.0,and a hydrogen circulation rate within the range of about 1,000 to about50,000 standard cubic feet per barrel. In view of the fact that thereactions being effected are exothermic in nature, an increasingtemperature gradient is experienced as the hydrogen and feed stocktraverses the catalyst bed. For any given hydrogen-consuming process, itis desirable to maintain the maximum catalyst bed temperature belowabout 900°F., which temperature is virtually identical to thatconveniently measured at the outlet of the reaction zone.Hydrogen-consuming processes are conducted at a temperature in the rangeof about 200°F. to about 900°F., and it is intended herein that thestated temperature of operation alludes to the maximum catalyst bedtemperature. In order to assure that the catalyst bed temperature doesnot exceed the maximum allowed for a given process, the use ofconventional quench streams, either normally liquid or gaseous,introduced at one or more intermediate loci of the catalyst bed, may beutilized. In some of the hydrocarbon hydroprocesses encompassed by thepresent invention, and especially where hydrocracking a heavyhydrocarbonaceous material to produce lower-boiling hydrocarbonproducts, that portion of the normally liquid product effluent boilingabove the end point of the desired product will be recycled to combinewith the fresh hydrocarbon charge stock. In these situations, thecombined liquid feed ratio (defined as volumes of total liquid charge tothe reaction zone per volume of fresh feed charge to the reaction zone)will be within the range of about 1.1 to about 6.0.

Specific operating conditions, processing techniques, particularcatalytic composites and other individual process details will be givenin the following detailed description of several of the hydrocarbonhydroprocesses to which the present invention is applicable. These willbe presented by way of examples given in conjunction withcommercially-scaled operating units. In presenting these examples, it isnot intended that the invention be limited to the specificillustrations, nor is it intended that a given process be limited to theparticular operating conditions, catalytic composite, processingtechniques, charge stock, etc. It is understood, therefore, that thepresent invention is merely illustrated by the specifics hereinafter setforth.

EXAMPLE I

In this example, the present invention is illustrated as applied to thehydrogenation of aromatic hydrocarbons such as benzene, toluene, thevarious xylenes, naphthalenes, etc., to form the corresponding cyclicparaffins. When applied to the hydrogenation of aromatic hydrocarbons,which are contaminated by sulfurous compounds, primarily thipheniccompounds, the process is advantageous in that it affords 100.0%conversion without the necessity for the substantially complete priorremoval of the sulfur compounds. The corresponding cyclic paraffins,resulting from the hydrogenation of the aromatic nuclei, includecompounds such as cyclohexane, mono-, di-, tri-substituted cyclohexanes,decahydronaphthalene, tetrahydronaphthalene, etc., which find widespreaduse as a variety of commercial industries in the manufacture of nylon,as solvents for various fats, oils, waxes, etc.

Aromatic concentrates are obtained by a multiplicity of techniques. Forexample, a benzene-containing fraction may be subjected to distillationto provide a heart-cut which contains the benzene. This is thensubjected to a solvent extraction process which separates the benzenefrom the normal or iso-paraffinic components, and the naphthenescontained therein. Benzene is readily recovered from the selectedsolvent by way of distillation, and in a purity of 99.0% or more.Heretofore, the hydrogenation of aromatic hydrocarbons, for examplebenzene, has been effected with a nickel-containing catalyst. This isextremely disadvantageous in many respects, and especially from thestandpoint that nickel is quite sensitive to the minor quantity ofsulfurous compounds which may be contained in the benzene concentrate.In accordance with the present process, the benzene is hydrogenated incontact with a non-acidic catalytic composite containing 0.01% to about2.0% by weight of a platinum or palladium component, from about 0.01% toabout 5.0% by weight of a germanium component from about 0.01% to about2% by weight of an iridium component and from about 0.01% to about 1.5%by weight of an alkalinous metal component. Operating conditions includea maximum catalyst bed temperature in the range of about 200°F. to about800°F., a pressure of from 500 to about 2,000 psig., a liquid hourlyspace velocity of about 1.0 to about 10.0 and a hydrogen circulationrate in an amount sufficient to yield a mole ratio of hydrogen tocyclohexane, in the product effluent from the last reaction zone, notsubstantially less than about 4.0:1. Although not essential, onepreferred operating technique involves the use of three reaction zones,each of which contains approximately one-third of the total quantity ofcatalyst employed. The process is further facilitated when the totalfresh benzene is added in three approximately equal portions, one eachto the inlet of each of the three reaction zones.

The catalyst utilized is a substantially halogen-free alumina carriermaterial combined with about 0.50% by weight of germanium, 0.375% byweight of iridium, 0.375% by weight of platinum, and about 0.90% byweight of lithium, all of which are calculated on the basis of theelemental metals. The hydrogenation process will be described inconnection with a commercially-scaled unit having a total fresh benzenefeed capacity of about 1,488 barrels per day. Make-up gas in an amountof about 741.6 mols/hr. is admixed with 2,396 Bbl./day (about 329mols/hr.) of a cyclohexane recycle stream, the mixture being at atemperature of about 137°F., and further mixed with 96.24 mols/hr. (582Bbl./day) of the benzene feed; the final mixture constitutes the totalcharge to the first reaction zone.

Following suitable heat-exchange with various hot effluent streams, thetotal feed to the first reaction zone is at a temperature of 385°F. anda pressure of 460 psig. The reaction zone effluent is at a temperatureof 606°F. and a pressure of about 450 psig. The total effluent from thefirst reaction zone is utilized as a heat-exchange medium, in a streamgenerator, whereby the temperature is reduced to a level of about 545°F.The cooled effluent is admixed with about 98.5 moles per hour (596Bbl./day) of fresh benzene feed, at a temperature of 100°F.; theresulting temperature is 400°F., and the mixture enters the secondreaction zone at a pressure of about 440 psig. The second reaction zoneeffluent, at a pressure of 425 psig. and a temperature of 611°F., isadmixed with 51.21 mols/hr. (310 Bbl./day) of fresh benzene feed, theresulting mixture being at a temperature of 578°F. Following its use asa heat-exchange medium, the temperature is reduced to 400°F., and themixture enters the third reaction zone at a pressure of 415 psig. Thethird reaction zone effluent is at a temperature of about 500°F. and apressure of about 400 psig. Through utilization as a heat-exchangemedium, the temperature is reduced to a level of about 244°F., andsubsequently reduced to a level of about 115°F. by use of an air-cooledcondenser. The cooled third reaction zone effluent is introduced into ahigh pressure separator, at a pressure of about 370 psig.

A hydrogen-rich vaporous phase is withdrawn from the high pressureseparator and recycled by way of compressive means, at a pressure ofabout 475 psig., to the inlet of the first reaction zone. A portion ofthe normally liquid phase is recycled to the first reaction zone as thecyclohexane concentrate hereinbefore described. The remainder of thenormally liquid phase is passed into a stabilizing column functioning atan operating pressure of about 250 psig., a top temperature of about160°F. and a bottom temperature of about 430°F. The cyclohexane productis withdrawn from the stabilizer as a bottoms stream, the overheadstream being vented to fuel. The cyclohexane concentrate is recovered inan amount of about 245.80 moles per hour, of which only about 0.60 molesper hour constitutes other hexanes. In brief summation, of the 19,207pounds per hour of fresh benzene feed, 20,685 pounds per hour ofcyclohexane product is recovered.

EXAMPLE II

Another hydrocarbon hydroprocessing scheme, to which the presentinvention is applicable, involves the hydrorefining of coke-forminghydrocarbon distillates. The hydrocarbon distillates are generallysulfurous in nature, and contain mono-olefinic, di-olefinic and aromatichydrocarbons. Through the utilization of a catalytic compositecomprising a germanium component, an iridium component and a platinum orpalladium component, increased selectivity and stability of operation isobtained; selectivity is most noticeable with respect to the retentionof aromatics, and in hydrogenating conjugated di-olefinic andmono-olefinic hydrocarbons. Such charge stocks generally result fromdiverse conversion processes including the catalytic and/or thermalcracking of petroleum, sometimes referred to as pyrolysis, thedestructive distillation of wood or coal, shale oil retorting, etc. Theimpurities in these distillate fractions must necessarily be removedbefore the distillates are suitable for their intended use, or whichwhen removed, enhance the value of the distillate fraction for furtherprocessing. Frequently, it is intended that these charge stocks besubstantially desulfurized, saturated to the extent necessary to removethe conjugated di-olefins, while simultaneously retaining the aromatichydrocarbons. When subjected to hydrorefining for the purpose ofremoving the contaminating influences, there is encountered difficultyin effecting the desired degree of reaction due to the formation of cokeand other carbonaceous material.

As utilized herein, "hydrogenating" is intended to be synonymous with"hydrorefining". The purpose is to provide a highly selective and stableprocess for hydrogenating coke-forming hydrocarbon distillates, and thisis accomplished through the use of a fixed-bed catalytic reaction systemutilizing a catalyst comprising a germanium component, an iridiumcomponent and a platinum or palladium component. There exists twoseparate, desirable routes for the treatment of coke-formingdistillates, for example a pyrolysis naphtha byproduct. One such routeis directed toward a product suitable for use in certain gasolineblending. With this as the desired object, the process can be effectedin a single stage, or reaction zone, with the catalytic compositehereinafter specifically described as the first-stage catalyst. Theattainable selectivity in this instance resides primarily in thehydrogenation of highly reactive double bonds. In the case of conjugateddi-olefins, the selectivity afforded restricts the hydrogenation toproduce mono-olefins, and, with respect to the styrenes, for example,the hydrogenation is inhibited to produce alkyl benzenes without "ring"saturation. The selectivity is accomplished with a minimum of polymerformation either to "gums", or lower molecular weight polymers whichwould necessitate a re-running of the product before blending togasoline would be feasible. Other advantages of restricting thehydrogenating of the conjugated di-olefins, such as 1,5 normal hexadieneare not unusually offensive in suitably inhibited gasolines in somelocales, and will not react in this stage. Some fresh charge stocks aresufficiently low in mercaptan sulfur content that direct gasolineblending may be considered, although a mild treatment for mercaptansulfur removal might be necessary. These considerations are generallyapplicable to foreign markets, particularly European, where olefinic andsulfur-containing gasolines are not too objectionable. It must be notedthat the sulfurous compounds, and the mono-olefins, whether virgin, orproducts of di-olefin partial saturation, are unchanged in the single,or first-stage reaction zone. Where however the desired end result isaromatic hydrocarbon retention, intended for subsequent extraction, thetwo-stage route is required. The mono-olefins must be substantiallysaturated in the second stage to facilitate aromatic extraction by wayof currently utilized methods. Thus, the desired necessary hydrogenationinvolves saturation of the mono-olefins, as well as sulfur removal, thelatter required for an acceptable ultimate aromatic product. Attendantupon this is the necessity to avoid even partial saturation of aromaticnuclei.

With respect to one catalytic composite, its principal function involvesthe selective hydrogenation of conjugated diolefinic hydrocarbons tomono-olefinic hydrocarbons. The particular catalytic composite possessesunusual stability notwithstanding the presence of relatively largequantities of sulfurous compounds in the fresh charge stock. Thecatalytic composite comprises an alumina-containing refractory inorganicoxide, a germanium component, an iridium component, a platinum orpalladium component and an alkali-metal component, the latter beingpreferably potassium and/or lithium. It is especially preferred, for usein this particular hydrocarbon hydroprocessing scheme, that thecatalytic composite be substantially free from any "acid-acting"propensities. The catalytic composite, utilized in the second reactionzone for the primary purpose of effecting the destructive conversion ofsulfurous compounds into hydrogen sulfide and hydrocarbons, is acomposite of an alumina-containing refractory inorganic oxide, aplatinum or palladium component, an iridium component, and a germaniumcomponent. Through the utilization of a particular sequence ofprocessing steps, and the use of the foregoing described catalystcomposites, the formation of high molecular weight polymers andco-polymers is inhibited to a degree which permits processing for anextended period of time. Briefly, this is accomplished by initiating thehydrorefining reactions at temperatures below about 500°F., at whichtemperatures the coke-forming reactions are not promoted. The operatingconditions within the second reaction zone are such that the sulfurouscompounds are removed without incurring the detrimental polymerizationreactions otherwise resulting were it not for the saturation of theconjugated di-olefinic hydrocarbons within the first reaction zone.

The hydrocarbon distillate charge stock, for example a light naphthaby-product from a commercial cracking unit designed and operated for theproduction of ethylene, having a gravity of about 34.0° API, a brominenumber of about 35.0, a diene value of about 17.5 and containing about1,600 ppm. by weight of sulfur and 75.9 vol.% aromatic hydrocarbons, isadmixed with recycled hydrogen. This light naphtha co-product has aninitial boiling point of about 164°F. and an end boiling point of about333°F. The hydrogen circulation rate is within the range of from about1,000 to about 10,000 scf./Bbl., and preferably in the narrower range offrom 1,500 to about 6,000 scf./Bbl. The charge stock is heated to atemperature such that the maximum catalyst temperature is in the rangeof from about 200°F. to about 500°F., by way of heat-exchange withvarious product effluent streams, and is introduced into the firstreaction zone at an LHSV in the range of about 0.5 to about 10.0. Thereaction zone is maintained at a pressure of from 400 to about 1,000psig., and preferably at a level in the rnage of from 500 psig. to about900 psig.

The temperature of the product effluent from the first reaction zone isincreased to a level above about 500°F., and preferably to result in amaximum catalyst temperature in the range of 600°F. to 900°F. When theprocess is functioning efficiently, the diene value of the liquid chargeentering the second catalytic reaction zone is less than about 1.0 andoften less than about 0.3. The conversion of nitrogenous and sulfurouscompounds, and the saturation of mono-olefins, contained within thefirst zone effluent, is effected in the second zone. The secondcatalytic reaction zone is maintained under an imposed pressure of fromabout 400 to about 1,000 psig., and preferably at a level of from about500 to about 900 psig. The two-stage process is facilitated when thefocal point for pressure control is the high pressure separator servingto separate the product effluent from the second catalytic reactionzone. It will, therefore, be maintained at a pressure slightly less thanthe first catalytic reaction zone, as a result of fluid flow through thesystem. The LHSV through the second reaction zone is about 0.5 to about10.0, based upon fresh feed only. The hydrogen circulation rate will bein a range of from 1,000 to about 10,000 scf./Bbl., and preferably fromabout 1,000 to about 8,000 scf./Bbl. Series-flow through the entiresystem is facilitated when the recycle hydrogen is admixed with thefresh hydrocarbon charge stock. Make-up hydrogen, to supplant thatconsumed in the overall process, may be introduced from any suitableexternal source, but is preferably introduced into the system by way ofthe effluent line from the first catalytic reaction zone to the secondcatalytic reaction zone.

With respect to the naphtha boiling range portion of the producteffluent, the sulfur concentration is about 0.1 ppm., the aromaticconcentration is about 75.1% by volume, the bromine number is less thanabout 0.3 and the diene value is essentially "nil".

With charge stocks having exceedingly high diene values, a recyclediluent is employed in order to prevent an excessive temperature rise inthe reaction system. Where so utilized, the source of the diluent ispreferably a portion of the normally liquid product effluent from thesecond catalytic reaction zone. The precise quantity of recycle materialvaries from feed stock to feed stock; however, the rate at any giventime is controlled by monitoring the diene value of the combined liquidfeed to the first reaction zone. As the diene value exceeds a level ofabout 25.0, the quantity of recycle is increased, thereby increasing thecombined liquid feed ratio; when the diene value approaches a level ofabout 20.0, or less, the quantity of recycle diluent may be lessened,thereby decreasing the combined liquid feed ratio.

With another so-called pyrolysis gasoline, having a gravity of about36.4° API, containing 600 ppm. by weight of sulfur, 78.5% by volume ofaromatics, and having a bromine number of 45 and a diene value of 25.5it is initally processed in a first reaction zone containing a catalyticcomposite of alumina, 0.5% by weight of lithium, 0.20% by weight ofpalladium, 0.375% by weight of iridium and 0.375% by weight ofgermanium, calculated as the elements. The fresh feed charge rate is3,300 Bbl./day, and this is admixed with 2,475 Bbl./day of the normallyliquid diluent. Based upon fresh feed only, the LHSV is 2.5 and thehydrogen circulation rate is 1,750 scf./Bbl. The charge is raised to atemperature of about 250°F., and enters the first reaction zone at apressure of about 840 psig. The product effluent emanates from the firstreaction zone at a pressure of about 830 psig. and a temperature ofabout 350°F. The effluent is admixed with about 660 scf./Bbl. of make-uphydrogen, and the temperature is increased to a level of about 545°F.,the heated stream is introduced into the second reaction zone under apressure of about 790 psig. The LHSV, exclusive of the recycle diluent,is 2.5, and the hydrogen circulation rate is about 1,500. The secondreaction zone contains a catalyst of a composite of alumina, 0.375% byweight of platinum, 0.375% by weight of iridium and 0.25% by weight ofgermanium. The reaction product effluent is introduced following its useas a heat-exchange medium and further cooling, to reduce its temperaturefrom 620°F. to a level of 100°F., into a high-pressure separator at apressure of about 750 psig. The normally liquid stream from the coldseparator is introduced into a reboiled stripping column for hydrogensulfide removal and depentanization. The hydrogen sulfide strippingcolumn functions at conditions of temperature and pressure required toconcentrate a C₆ to C₉ aromatic stream as a bottoms fraction. Withrespect to the overall product distribution, only 690 lbs./hr. ofpentanes and lighter hydrocarbons is indicated in the stripper overhead.The aromatic concentrate is recovered in an amount of about 40,070lbs./hr. (the fresh feed is 40,120 lbs./hr); these results are achievedwith a hydrogen consumption of only 660 scf./Bbl. With respect to thedesired product, the aromatic concentration is 78.0, the sulfurconcentration is less than 1.0 ppm. by weight, and the diene value isessentially nil.

EXAMPLE III

This example is presented to illustrate still another hydrocarbonhydroprocessing scheme for the improvement of the jet fuelcharacteristics of sulfurous kerosene boiling range fractions. Theimprovement is especially noticeable in the IPT Smoke Point, theconcentration of aromatic hydrocarbons and the concentration of sulfur.A two-stage process wherein desulfurization is effected in the firstreaction zone at relatively mild severities which result in a normallyliquid product effluent containing from about 15 to about 35 ppm. ofsulfur by weight. Aromatic saturation is the principal reaction effectedin the second reaction zone, having disposed therein a catalyticcomposite of alumina, a halogen component, a platinum or palladium,component, an iridium component and a germanium component.

Suitable charge stocks are kerosene fractions having an initial boilingpoint as low as about 300°F., and an end boiling point as high as about575°F., and, in some instances, up to 600°F. Examplary of such kerosenefractions are those boiling from about 300°F. to about 550°F., from330°F. to about 500°F., from 330°F. to about 530°F., etc. As a specificexample, a kerosene obtained from hydrocracking a Mid-continent slurryoil, having a gravity of about 30.5° API, an initial boiling point ofabout 388°F., an end boiling point of about 522°F., has an IPT SmokePoint of 17.1 mm., and contains 530 ppm. of sulfur and 24.8% by volumeof aromatic hydrocarbons. Through the use of the catalytic process ofthe present invention, the improvement in the jet fuel quality of such akerosene fraction is most significant with respect to raising the IPTSmoke Point, and reducing the concentration of sulfur and the quantityof aromatic hydrocarbons. Specifications regarding the poorest qualityof jet fuel, commonly referred to as Jet-A, Fet-A1 and Jet-B call for asulfur concentration of about 0.3% by weight maximum (3,000 ppm.), aminimum IPT Smoke Point of 25 mm. and a maximum aromatic concentrationof about 20.0 vol. %.

The charge stock is admixed with circulating hydrogen in an amountwithin the range of from about 1,000 to about 2,000 scf./Bbl. Thismixture is heated to a temperature level necessary to control themaximum catalyst bed temperature below about 750°F., and preferably notabove 700°F., with a lower catalyst bed temperature of about 600°F. Thecatalyst, a well known standard desulfurization catalyst containingabout 2.2% by weight of cobalt and about 5.7% by weight of molybdenum,composited with alumina is disposed in a reaction zone maintained underan imposed pressure in the range of from about 500 to about 1,000 psig.The LHSV is in the range of about 0.5 to about 10.0, and preferably fromabout 0.5 to about 5.0. The total product effluent from this firstcatalytic reaction zone is separated to provide a hydrogen-rich gaseousphase and a normally liquid hydrocarbon stream containing 15 ppm. toabout 35 ppm. of sulfur by weight. The normally liquid phase portion ofthe first reaction zone effluent is utilized as the fresh feed chargestock to the second reaction zone. In this particular instance, thefirst reaction zone decreases the sulfur concentration to about 25 ppm.,the aromatic concentration to about 16.3% by volume, and has increasedin the IPT Smoke Point to a level of about 21.5 mm.

The catalytic composite within the second reaction zone comprisesalumina, 0.375% by weight of platinum, 0.375% by weight of iridium,0.30% by weight of germanium and about 0.60% by weight of combinedchloride, calculated on the basis of the elements. The reaction zone ismaintained at a pressure of about 400 to about 1,500 psig., and thehydrogen circulation rate is in the range of 1,500 to about 10,000scf./Bbl. The LHSV, hereinbefore defined, is in the range of from about0.5 to about 5.0, and preferably from about 0.5 to about 3.0. It ispreferred to limit the catalyst bed temperature in the second reactionzone to a maximum level of about 750°F. With a catalyst of thisparticular chemical and physical characteristics, optimum aromaticsaturation, processing a feed stock containing from about 15 to about 35ppm. of sulfur, is effected at maximum catalyst bed temperatures in therange of about 625°F. to about 750°F. With respect to the normallyliquid kerosene fraction, recovered from the condensed liquid removedfrom the total product effluent, the sulfur concentration is effectivelynil, being about 0.1 ppm. The quantity of aromatic hydrocarbons has beendecreased to a level of about 0.75% by volume, and the IPT Smoke Pointhas been increased to about 36.3 mm.

With respect to another kerosene fraction, having an IPT Smoke Point ofabout 20.5 mm., an aromatic concentration of about 19.3 vol.% and asulfur concentration of about 17 ppm. by weight, the same is processedin a catalytic reaction zone at a pressure of about 850 psig. and amaximum catalyst bed temperature of about 725°F. The LHSV is about 1.35,and the hydrogen circulation rate is about 8,000 scf./Bbl. The catalyticcomposite disposed within the reaction zone comprises alumina, 0.25% byweight of platinum, 0.25% by weight of iridium, 0.40% by weight ofgermanium, about 0.35% by weight of combined chloride and 0.35% byweight of combined fluoride. Following separation and distillation, toconcentrate the kerosene fraction, analyses indicate that the SmokePoint has been increased to a level of about 36.9 mm., the aromaticconcentration has been lowered to about 0.6% by volume and the sulfurconcentration is essentially nil.

EXAMPLE IV

This illustration of a hydrocarbon hydroprocessing scheme, encompassedby my invention is one which involves hydrocracking heavyhydrocarbonaceous material into lower-boiling hydrocarbon products. Inthis instance, the preferred catalysts contain a germanium component, aplatinum or palladium component, an iridium component, combined with acrystalline aluminosilicate-carrier material, preferably faujasite, andstill more preferably one which is at least 90.0% by weight zeolitic.

Most of the virgin stocks, intended for hydrocracking, are contaminatedby sulfurous compounds and nitrogenous compounds, and, in the case ofthe heavier charge stocks, various metallic contaminants, insolubleasphalts, etc. Contaminated charge stocks are generally hydrorefined inorder to prepare a charge suitable for hydrocracking. Thus, thecatalytic process of the present invention can be beneficially utilizedas the second stage of a two-stage process, in the first stage of whichthe fresh feed is hydrorefined.

Hydrocracking reactions are generally effected at elevated pressures inthe range of about 800 to about 5,000 psig., and preferably at someintermediate level of 1,000 to about 3,500 psig. Liquid hourly spacevelocities of about 0.25 to about 10.0 will be suitable, the lower rangegenerally reserved for the heavier stocks. The hydrogen circulation ratewill be at least about 3,000 scf./Bbl., with an upper limit of about50,000 scf./Bbl., based upon fresh feed. For the majority of feedstocks, hydrogen circulation in the range of 5,000 to 20,000 scf./Bbl.will suffice. With respect to the LHSV, it is based upon fresh feed,notwithstanding the use of recycle liquid providing a combined liquidfeed ratio in the range of about 1.25 to about 6.0. The operatingtemperature again alludes to the temperature of the catalyst within thereaction zone, and is in the range of about 400°F. to about 900°F. Sincethe principal reactions are exothermic in nature, the increasingtemperature gradient, experienced as the charge stock traverses thecatalyst bed, results in an outlet temperature higher than that at theinlet to the catalyst bed. The maximum catalyst temperature should notexceed 900°F., and it is generally a preferred technique to limit thetemperature increase to 100°F. or less.

Although amorphous composites of alumina and silica, containing fromabout 10.0% to about 90.0% by weight of the latter, are suitable for usein the catalytic composite employed in the present process, a preferredcarrier material constitutes a crystalline aluminosilicate, preferablyfaujasite, of which at least about 90.0% by weight is zeolitic. Thiscarrier material, and a method of preparing the same, have hereinbeforebeen described. Generally, the germanium component will be used in anamount sufficient to result in a final catalytic composite containingabout 0.01% to about 5.0% by weight. The iridium component will be usedin an amount sufficient to result in a final catalytic compositecontaining about 0.01% to about 2% by weight. The platinum or palladiumcomponent is generally present in an amount within the range of about0.01% to about 2.0% by weight, and may exist within the composite as acompound such as an oxide, sulfide, halide, etc. Another possibleconstituent of the catalyst is a halogen component, either fluorine,chlorine, iodine, bromine, or mixtures thereof. Of these, it ispreferred to utilize a catalyst containing fluorine and/or chlorine. Thehalogen component will be composited with the carrier material in such amanner as results in a final composite containing about 0.1% to about1.5% by weight of halogen, calculated on an elemental basis.

A specific illustration of this hydrocarbon hydroprocessing techniqueinvolves the use of a catalytic composite of about 0.4% by weight ofplatinum, 0.375% by weight of iridium, 0.7% by weight of combinedchlorine, and 0.4% by weight of germanium, combined with a crystallinealuminosilicate material of which about 90.9% by weight constitutesfaujasite. This catalyst is intended for utilization in the conversionof 16,000 Bbl./day of a blend of light gas oils to produce maximumquantities of a heptane-400°F. gasoline boiling range fraction. Thecharge stock has a gravity of 33.8° API, contains 0.19% by weight ofsulfur (1,900 ppm.) and 67 ppm. by weight of nitrogen, and has aninitial boiling point of 369°F., a 50% volumetric distillationtemperature of 494°F. and an end boiling point of 655°F. The chargestock is initially subjected to a clean-up operation at maximum catalysttemperature of 750°F., a combined feed ratio of 1.0 an LHSV of 2.41 witha hydrogen circulation rate of about 5000 scf./Bbl. The pressure imposedupon the catalyst within the reaction zone is about 1,500 psig. Since atleast a portion of the blended gas oil charge stock will be convertedinto lower-boiling hydrocarbon products, the effluent from this clean-upreaction zone is separated to provide a normally liquid, 400°F.-pluscharge for the hydrocracking reaction zone containing theplatinum-iridium-germaniumchloride catalyst. The pressure imposed uponthe second reaction zone is about 1,500 psig., and the hydrogencirculation rate is about 8,000 scf./Bbl. The original quantity of freshfeed to the clean-up reaction zone is about 16,000 Bbl./day; followingseparation of the first zone effluent to provide the 400°F.-plus chargeto the second reaction zone, the charge to the second reaction zone isin an amount of about 12,150 Bbl./day, providing an LHSV of 0.85. Thetemperature at the inlet to the catalyst bed is 665°F., and aconventional hydrogen quench stream is utilized to maintain the maximumreactor outlet temperature at about 700°F. Following separation of theproduct effluent from the second reaction zone, to concentrate thedesired gasoline boiling range fraction, the remaining 400°F.-plusnormally liquid material, in an amount of 7,290 Bbl./day, is recycled tothe inlet of the second reaction zone, thus providing a combined liquidfeed ratio thereto of about 1.60. In the following table, there isindicated the product yield and distribution of this process. Withrespect to normally liquid hydrocarbons, for convenience includingbutanes, the yields are given in vol. %; with respect to the normallygaseous hydrocarbons, ammonia and hydrogen sulfide, the yields are givenin terms of wt. %. With respect to the first reaction zone, the hydrogenconsumption is 1.31% by weight of the fresh feed (741 scf./Bbl.), andfor the hydrocracking reaction zone, 1.26% by weight of the fresh feedcharge stock, or 713 scf./Bbl.

                  TABLE                                                           ______________________________________                                        Hydrocracking Product Yield and Distribution                                  ______________________________________                                        Component     Stage I   Stage II  Total                                       ______________________________________                                        Ammonia       0.01      --        0.01                                        Hydrogen Sulfide                                                                            0.21      --        0.21                                        Methane       0.12      0.02      0.14                                        Ethane        0.22      0.40      0.62                                        Propane       1.03      3.48      4.51                                        Butanes       3.90      14.66     18.56                                       Pentanes      3.04      11.28     14.32                                       Hexanes       3.00      11.21     14.21                                       C.sub.7 -400°F.                                                                      18.85     49.56     68.41                                       400°F.-plus                                                                          75.92*    --        --                                          ______________________________________                                         *Charge to Stage II                                                      

With respect to both the butane product and pentane product, the formeris indicated as being about 68.0% isobutanes, while the latterconsitutes about 93.0% isopentanes. An analysis of the combinedpentane/hexane fraction indicates a gravity of 82.6° API, a clearresearch octane rating of 85.0 and a leaded research octane rating of99.0; it will be noted that this consitutes an excellent blendingcomponent for motor fuel. The desired heptane-400°F. product indicates agravity of 48.8° API, a clear research octane rating of 72.0 and aleaded research octane rating of 88.0. This gasoline boiling rangefraction constitutes about 34.0% by volume paraffins, 36.0% by volumenaphthenes and 30.0% by volume aromatic hydrocarbons. It will berecognized that this gasoline boiling range fraction constitutes anexcellent charge stock for a catalytic reforming unit to improve themotor fuel characteristics thereof.

The foregoing specification, and particularly the examples, indicatesthe method by which the present invention is effected, and the benefitsafforded through the utilization thereof.

I claim as my invention:
 1. A hydrocarbon hydroprocess for improving the jet fuel characteristics of a sulfurous kerosene boiling range fraction, which process comprises reacting said kerosene fraction with hydrogen at conditions selected to effect chemical consumption of hydrogen in a catalytic reaction zone containing a catalytic composite of a platinum or a palladium component, an iridium component, a germanium component and a porous carrier material, substantially all of the platinum or palladium component and the iridium component being in the elemental metallic state and the germanium component being in an oxidation state above that of the elemental state, and separating the resulting reaction zone effluent to recover a normally liquid kerosene fraction having improved jet fuel characteristics.
 2. The process of claim 1 further characterized in that said catalytic composite contains from about 0.01% to about 2% by weight of said platinum or palladium component, from about 0.1% to about 2% by weight of said iridium component and from about 0.01% to about 5% by weight of said germanium component, calculated on an elemental basis.
 3. The process of claim 1 further characterized in that said catalytic composite contains from about 0.1% to about 1.5% by weight of a halogen component, on an elemental basis.
 4. The process of claim 1 further characterized in that said carrier material is alumina.
 5. The process of claim 1 further characterized in that said conditions include a pressure from about 400 psig. to about 1,500 psig., a liquid hourly space velocity from about 0.1 to about 10, a hydrogen circulation rate from about 1,000 to about 50,000 scf./Bbl. and a maximum catalyst temperature from about 200°F. to about 750°F. 